Trigger-operated magazine indexing means for a semiautomatic grenade launcher

ABSTRACT

A SEMIAUTOMATIC GRENADE LAUNCHER WHEREIN EACH OF THE INDIVIDUAL FIRING CHAMBERS IN A TRANSVERSELY FED MAGAZINE ARE SUCCESSIVELY RETAINED IN FIRING ALIGNMENT WITH A LONGITUDINALLY SLIDABLE BARREL FIRST BY A DETENT BIASED INTO RELEASABLE ENGAGEMENT WITH THE MAGAZINE AND THEREAFTER BY THE ENGAGEMENT OF THE BREECH END OF THE BARREL IN THE FIRING CHAMBER IN ALIGNMENT THEREWITH, AND WHEREIN THE FIRING RETRACTION OF THE TRIGGER IS UTILIZED TO FUNCTION SEPARATE CAMS FOR ACCOMPLISHING THE REQUIRED ACTUATION OF BOTH THE BARREL AND THE DETENT PRIOR TO THE FIRING OF THE CARTRIDGE, THE ENGAGEMENT BETWEEN THE BARREL AND EACH FIRING CHAMBER BEING ALSO ARRANGED TO SEAL THE JUNCTION THEREBETWEEN AGAINST THE ESCAPE OF THE DISCHARGE GASES GENERATED BY THE FIRING OF THE CARTRIDGE.

March 9, 1971 c. E. LANIZZANI 3,563,349

TRIGGER-OPERATED MAGAZINE INDEXING MEANS FOR A SEMIAUTOMATIC GRENADE LAUNCHER 4 Sheets-Sheet 1 Filed May 12, 1969 NO WN ww mu l N07 \JH: N im mm m H OO mm I 4 I I l l I r l l l I I H I In KR INVENTOR Charles Eluuizzuni March 9, 1971 c. E. LANIZZANI 3,568,349

TRIGGER-OPERATED MAGAZINE INDEXING MEANS FOR A SEMIAUTOMATIC GRENADE LAUNCHER Filed May 12, 1969 4 Sheets-Sheet 2 ;g: :i:f 94 4, no 3| 10s 96 r 7 g INVENTOR EhuflesELunizzuni MM. 8 21 2 ,W W 8, W F- ATTORNEYS March 9, 1971 c. E. LANIZZANI A SEMIAUTOMATIC GRENADE LAUNCHER 4 Sheets-Sheet 5 Filed May 12, 1969 m T HW w E w i m mp I mm g I 11 Ii om i| n NN 0 1% mm l\ A 3 m H (K E .W .m. 9'

vv 5 D. 09 3 m9 J o 09 m: R vi mm. mm mm 3% \|k.fli| 1. r4 l NH I P///A///// 1 x I v9 o 09 mm I 3 \w I L IILLl/l March 9, 1971 c, LANIZZAM 3,568,349

' TRIGGER-OPERATED MAGAZINE INDEXING MEANS FOR A SEMIAUIOMATIC GRENADE LAUNCHER Filed May 12, 1969 4 Sheets-Sheet 4 INVENTOR '22 us EhuflEsElunizznni lie-M 5 Bl #146 M 0W5 M ATTORNEYS j United States Patent O US. Cl. 42-395 14 Claims ABSTRACT OF THE DISCLOSURE A semiautomatic grenade launcher wherein each of the individual firing chambers in a transversely fed magazine are successively retained in firing alignment with a longitudinally slidable barrel first by a detent biased into releasable engagement with the magazine and thereafter by the engagement of the breech end of the barrel in the firing chamber in alignment therewith, and wherein the firing retraction of the trigger is utilized to function separate cams for accomplishing the required actuation of both the barrel and the detent prior to the firing of the cartridge, the engagement between the barrel and each firing chamber being also arranged to seal the junction therebetween against the escape of the discharge gases generated by the firing of the cartridge.

The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION This invention relates to shoulder-held firearms for firing grenade ammunition and is more particularly directed to a semiautomatic firearm wherein the ammunition is successively fed into firing position by a transversely slidable magazine.

Although considerable progress has been made in providing grenade launcher firearms, or separate attachments to existing firearms, with a capacity for semiautomatic fire, none of these prior design efforts has met all the military requirements imposed thereon. One of the chief problems has been the diificulty encountered in automatically feeding the relatively bulky grenade cartridges into firing position during each cycle of operation. In one design, the barrel is arranged to be pulled forwardly by the passage of the projectile therethrough to permit a new cartridge to be fed into axial alignment therewith in position to be chambered by the return of the barrel to battery position. The drawbacks in this particular approach are the length of the travel required of the barrel and the relatively complicated mechanism involved in unlocking and locking the barrel in battery position during each firing cycle. Another design utilizes a fixed barrel into which each grenade cartridge is successively rammed prior to firing and from which the fired case is extracted subsequent to firing. Due to the excessive weight and the relatively complicated nature of the mechanisms required to complete the ramming and extracting portions of each cycle of firearm operation this type of design effort has not been accepted. A third approach relies on the use of a unitary magazine provided with separate laterally disposed firing chambers for the grenade cartridges. Such magazine is slidably mounted in a feedway extending transversely through the firearm and is arranged so that the firing of each cartridge will automatically index the next adjacent cartridge into firing alignment with the barrel. However, the undesirable factors in this design Patented Mar. 9, 1971 have been the difificulty of coordinating the feeding and firing functions of the launcher as well as the loss of the discharge gases through the junction between the forward face of each firing chamber in the magazine and the breech end of the barrel. It has been found that any reduction in the relatively low pressure provided by the grenade type ammunition produces an unacceptable reduction in the required minimum range as well as an undesirable variation in the accuracy of fire.

Accordingly, it is a primary object of this invention to provide a grenade launching firearm with improved means for automatically indexing a transversely slidable magazine to successively position each of a plurality of grenade cartridge therein into firing alignment with the barrel.

It is another object of this invention to provide magazine indexing means, as aforesaid, wherein the operation thereof is fully controlled by the firing actuation of the trigger.

A further object of this invention is the provision of a magazine indexing means, as aforesaid, wherein the component parts thereof are mounted in the firearm receiver to minimize the weight of the magazine.

An important object of the present invention is to provide a semiautomatic firearm, as aforesaid, with a reciprocating barrel arranged to retain the magazine against transverse feeding movement until the return of the trigger to the prefired position thereof repositions the indexing means for the next retention of the magazine.

It is another object of the present invention to provide a semiautomatic firearm, as aforesaid, wherein the retention of the magazine by the barrel is also utilized to seal the firing chamber in the magazine then in firing alignment therewith.

SUMMARY OF THE INVENTION It has been found that these objects can best be attained by a firearm in which a rectangular feedway extends transversely therethrough adjacent the breech end of the barrel to slidably receive a magazine provided with a plurality of separate laterally adjacent cartridge chambers. The transverse feeding movement imparted to the magazine by a negator spring acting against one end thereof is arranged to be successively interrupted by a vertically releasable detent so that each chamber in the magazine is temporarily retained in firing alignment with the barrel. In order to release the magazine for the feeding movement required to bring an unfired cartridge into firing alignment with the barrel, a floating cam is disposed between spaced lugs depending from a forward extension of the longitudinally slidable trigger utilized to actuate the firing mechanism. As the trigger is retracted, the floating cam is rearwardly displaced to depress the detent and free the magazine for the transverse movement required to feed the next firing chamber therein into axial alignment with the barrel.

However, immediately prior to the withdrawal of the detent from the magazine the retraction of the trigger is also utilized to cam the barrel into engagement with the firing chamber then in axial alignment therewith. This is accomplished by a cam plate fixed to the forward end of the trigger extension and engageable with a follower depending from the barrel. The firing retraction of the trigger actuates the cam plate to rotate the barrel in one direction while the return of the trigger to the prefired position thereof rotates the barrel in the opposite direction. The bottom of the firearm receiver is forwardly extended to terminate in a barrel-surrounding yoke provided with a helical cam slot arranged to be engaged by a vertical stud projecting from the top of the barrel. Thus, as the cam plate at the forward end of the trigger rotates the barrel, the helical cam slot in the stationary yoke acts on the vertical stud to actuate the barrel into or out of engagement with the forward end of the cartridgeholding chamber then in axial alignment therewith. The engagement between the barrel and the cartridge-holding chamber retains the magazine against the bias of the negator spring following the withdrawal of the indexing detent therefrom until the return of the trigger to the prefired position moves the floating cam out of engagement with the indexing detent. In addition, the engagement of the barrel in the firing chamber also serves to seal the junction therebetween against the escape of the discharge gases generated upon the firing of the cartridge therein.

BRIEF DESCRIPTION OF THE DRAWINGS The exact nature of the invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawings wherein:

FIG. 1 is a side elevational view of a firearm in which the present invention is incorporated and is broken away to show the position of the parts immediately prior to the firing retraction of the trigger;

FIG. 1a is a continuation of FIG. 1 showing the configuration of the yoke at the front end of the receiver extension and is additionally broken away to show the forward extension of the trigger;

FIG. 2 is a cross-sectional view taken along line 2--2 in FIG. 1 to show the manner in which the indexing detent retains the magazine against transverse feeding movement;

FIG. 3 is a cross-sectional view taken along line 3 3 in FIG. 1a showing the cam plate at the forward end of the trigger extension in engagement with the depending follower on the barrel;

FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 1a showing the configuration of the yoke surrounding the barrel;

FIG. 5 is a cross-sectional view taken along line 55 in FIG. 1 to show the details of the firing mechanism;

FIG. 6 is a fragmentary sectional view taken along line 66 in FIG. 3 to show the configuration of the cam opening in the cam plate connected to the forward end of the trigger extension;

FIG. 7 is a side elevational view of the firearm similar to that of FIGS. 1 and 1a but showing the position of the parts with the trigger retracted to the point immediately prior to the release of the hammer;

FIG. 8 is a fragmentary view taken along line 88 in FIG. 1a and looking down on the top of the yoke at the front end of the receiver to show the relationship between the helical cam slot and the vertical stud on the barrel prior to the rotation imparted thereto by the cam plate;

FIG. 9 is a view similar to FIG. 8 but showing the position of the parts upon the conclusion of the rotation imparted to the barrel during the retraction of the trigger;

FIG. 10 is a cross-sectional view taken along line 10 10 in FIG. 7 on an enlarged scale to show the details of the means for indexing the magazine;

FIG. 11 is a perspective view of the magazine with a grenade cartridge in each chamber thereof;

FIG. 12 is a perspective view of the floating cam in the magazine indexing mechanism; and

FIG. 13 is a perspective view of the detent utilized to retain the magazine against the transverse feeding bias imparted thereto by the negator spring.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring more particularly to the drawings wherein similar reference characters have been employed to designate corresponding parts throughout, the firearm in which the present invention is preferably incorporated essentially comprises a generally rectangular receiver 12, a housing 13 secured to the rear end of receiver 12 by screws 14 for enclosing a firing mechanism 15, and a conventional 4 drop stock 16 secured to the rear end of housing 13. If desired, stock 16 can be eliminated and the operating mechanism suitably attached to the underside of a conventional rifle. The forward end of receiver 12 is bored, as indicated at 18, to slidably receive the breech end of a barrel 20 for limited reciprocal movement, as will be hereinafter described. Immediately to the rear of bore 18 and in communication therewith, receiver 12 is provided with a transverse feedway 22 therethrough arranged to slidably receive a substantially rectangular magazine 24. As best shown in FIG. 2, the transverse feeding movement required of magazine 24 is imparted thereto by a negator spring 25 terminating in a coiled portion 26 disposed in abutment with the trailing end of magazine 24. The end of the uncoiled portion of spring 25 extends along a slot 27 of corresponding width formed across the floor of feedway 22 and is fastened thereto as by rivets 28.

The firing mechanism 15 essentially comprises a longitudinally slidable trigger 29 with an elongated body 30 extending forwardly through a corresponding channel 31 in receiver 12, a sear 32 pivoted to the top of trigger 29 at the rear end thereof, and a spring-biased hammer 33 pivotally mounted at the upper end thereof to extend downwardly in housing '13 and terminate in a depending finger 34. Trigger 29 is formed with longitudinal ribs 36 on opposite sides thereof slidably engageable in mating ways 38 within the interior of housing 13. The underside of housing 13 is longitudinally slotted, as indicated at 40, for the passage of the depending finger portion 42 of trigger 29 which is protected by a conventional trigger guard 44 spanning the length of slot 40'. A flexible coil spring 46 seated between trigger 29' and sear 32 normally biases the latter upwardly into position to contact hammer finger 34 and impart pivotal cocking movement thereto during the retraction of trigger 29. As sear 32 moves out of contact with finger 34 during the final portion of the retraction of trigger 29, hammer 33 is released to strike the protruding rear end of a spring-biased longitudinal firing pin 48 slidably disposed in the rear end of receiver 12.

As best shown in FIG. 11, magazine 24 preferably contains, but is not necessarily limited to, a trio of separate chambers 50 integrally joined in laterally adjacent fashion. Each chamber 50 is provided with a cylindrical opening 52 therethrough of sufficient diameter to receive the body but not the diametrically enlarged rim 54 at the rear end of a relatively bulky grenade cartridge 56. The length of opening 52 is such that the forward end thereof will preferably extend beyond the projectile end of cartridge 56 when rim 54 thereof is in contact with the rear face of chamber 50*. If desired, a spring-biased latch (not shown) may be installed in the rear of each chamber 50 to releasably retain the cartridge 56 therein. In addition, the forward end of each chamber 50 is chamfered, as indicated at 5'8, and is provided with a V-shaped groove 60 rearwardly adjacent chamfer 5 8. The exterior of magazine 24 is formed with longitudinally spaced vertical guide plates 62 arranged to slidably engage the front and rear walls of a transverse track 64 formed into both the top and bottom surfaces of feedway 22, as best shown in FIG. 1. A slot 66 extends transversely across the underside of magazine 24 substantially midway of guide plates 62 and includes an upwardly inclined recess 68 located in each of the areas between adjacent chambers 50. At the deeper end of each recess 68, a cylindrical stop block 70 with a threaded stem 72 is screwed into magazine 24 to project below the floor of slot 66.

The underside of receiver 12 is forwardly extended to form a concave trough 74 terminating in a pair of spaced parallel mounting lugs 76 projecting upwardly from the top of each sidewall for fixed engagement with a lug 78 depending from each end of yoke 80 encircling the upper half of barrel 20. A helical cam slot 82 is laterally disposed in the top of yoke 80 for slidable reception of a vertical stud 84 extending upwardly from the top of barrel 20. Trough 74 provides slidable support to barrel 20 and is longitudinally bifurcated along the forward portion thereof to form a rectangular passage 86 therethrough in communication with the front end of trigger body channel 31 in receiver 12. A concave cam plate 88 with outwardly flanged sides 90 is slidably seated in corresponding longitudinal ways 92 formed along the interior sidewalls of passage 86 in trough 74. Cam plate 88 is provided with a laterally disposed inclined cam slot 94 terminating in a linear dwell portion 96 at the front end thereof and a similar but shorter dwell portion 98 at the rear end thereof. Extending into slidable engagement with cam. slot 94 is a follower roller 100 depending from the underside of barrel 20. As cam plate 88 is longitudinally displaced, barrel 20 is rotated about the central axis thereof and consequently is correspondingly advanced or retracted by cam slot 82 in fixed yoke 80.

At the rear end of cam plate 88, a transversely extending rib 102 on the underside thereof projects downwardly into a mating groove 104 formed into the forward end of trigger body 30. A pair of cOil springs straddles trigger body 30 and are rearwardly seated in suitable longitudinal openings 1 10 located in the vertical wall formed by the rear end of passage 86 to bear against the rear edge of cam plate '88 for effecting the return thereof to a fully forward position.

Trigger body 30 includes a pair of longitudinally spaced lugs 112 depending from the underside thereof in position to transfer the longitudinal movement of trigger 29 to a floating cam 114 arranged to control the feeding movement of magazine 24. As best shown in FIG. 12, cam 114 is formed with a substantially rectangular body 116 centrally mounted on a larger rectangular base 118 and body 116 extends laterally outwardly therebeyond, as indicated at 120, to terminate in a rearwardly facing inclined cam surface 122. Receiver 12 is cut away along the underside thereof, as indicated at 123 in FIG. 1, to open the bottom of trigger body channel 31 from a point below the rear wall of transverse track 64 in feedway 22. A generally rectangular tray 126 is fixedly secured at the rear end thereof, as by a screw 128, to the underside of receiver 12 adjacent the start of cutaway portion 123. The floor of tray 126 is provided with a longitudinally extending vertical T-slot 124 for the slidable reception of base 118 of floating cam 114. The floor of tray 126 is also provided with a circular seat 130 spaced to one side of T-slot 124 for slidably receiving the lower end of a hollow cylindrical indexing plunger 132.

Plunger -132 extends upwardly through a suitable hole 133 in receiver 12 passing through a clearance opening 131 in negator spring 25 to terminate in an upwardly inclined rectangular ramp 134 forming a vertical detent shoulder 136 flush with the exterior of plunger 132. Plunger 132 is also vertically slabbed on one side thereof, as indicated at 135, to provide a ledge 137 and the upper portion of receiver hole 133 is correspondingly contoured to prevent rotation of plunger 132 therein. A coil spring 138 is housed within the interior of plunger 132 to bottom in circular seat 130 and bias plunger 132 upwardly for positioning shoulder 136 in the path of stop block 70 in the underside of magazine 24 to halt the transverse feeding movement imparted thereto by negator spring 25. Upward movement of plunger 132 is limited by contact between ledge 137 thereon and the underside of the upper reduced diameter portion of receiver hole 133. Extending outwardly from the lower end of plunger 132 into the path of cam surface 122 on floating cam 114 is a rectangular lug 140 preferably provided with a beveled upper edge 142. Thus, as earn 114 is carried to the rear by the slidable retraction of trigger 29, cam suface 122 contacts bevel 142 and rides over the top of lug 140 to depress plunger 132 and withdraw shoulder 136- thereon from engagerrrent with stop block 70 thereby releasing magazine 24 for transverse feeding actuation by negator spring 25.

In order to provide for the manual release of magazine 24 by plunger 132, an operating lever 144 is pivotally mounted between a pair of ears 146 depending from the rear end of tray 126. Lever 144 is vertically offset forwardly of the pivot point thereof to contact the underside of tray '126 and pass above the transverse arm 147 of an L-shaped retractor 148 fixed to the side of plunger 132 and arranged to extend downwardly therefrom through tray 126. Thus, when the rear end of opeating lever 144 is manually raised, the front end thereof is correspond ingly lowered to pull retractor 148 downwardly and thereby withdraw plunger 132 out of engagement with stop block 70 on the underside of magazine 24.

The forward end of tray 126 extends into a corresponding opening 150 in the rear end of an elongated plate 152 provided with upwardly and inwardly turned flanges 154 tightly fitted into corresponding slots 156 formed along the exterior of the forwardly extending receiver trough 74. Plate 152 closes the open bottom of trigger body channel 31 and also closes the open bottom of rectangular passage 86 in trough 74. The front end of plate 152 terminates in an upwardly inclined U-shaped portion 158 arranged to partially cover the open forward end of passage 86.

Firing pin 48 is arranged to be blocked against forward firing movement by a spring-biased safety 160' vertically disposed in receiver 12. In order to lift safety 160 into position to block firing pin 48, the rear portion of trigger body 30 is increased in height to form a sloped surface 162 engageable with the lower end of safety 160' during the return of trigger 29 to the prefired position thereof.

In order to load the firearm, a fluid magazine 24 is inserted into feedway 22 and advanced therealong against coiled portion 26 of negator spring 25 to effect the unrolling thereof. As the last stop block 70 on the underside of magazine 24 rides over ramp 134 on indexing plunger 132, the latter is biased upwardly by spring 138 to engage in inclined recess 68, as best shown in FIG. 2, and halt the retrograde movement imparted to magazine 24 by negator spring 25. In this position of magazine 24, the grenade cartridge 56 in the end chamber 50 thereof is disposed in firing alignment with barrel 20. As trigger 29 is initially retracted, the rearward movement imparted thereby to cam plate 88 causes cam slot 94 therein to act on follower roller 100 and rotate barrel 20 in a counterclockwise direction as viewed looking forwardly from the breech end thereof. During this rotation, cam slot 82 in yoke acts on vertical stud 84 of barrel 20 to force the latter to the rear, as illustrated in FIGS. 8 and 9, and bring the breech end thereof, which is also chamfered as indicated at 163, into mating contact with chamfer 58- in the forward end of firing chamber 50.

During this rearward movement of barrel 20, the forward depending lug 112 on trigger body 30 displaces floating cam 114 to act on indexing plunger 132 and withdraw vertical shoulder 136 thereon out of contact with stop block 70 protruding from the underside of magazine 24. However, by the time plunger 132 releases magazine 24, the breech end of barrel 20 is fully engaged in the chamfered front end of firing chamber 50 to continue the retention of magazine 24 against the bias of negator spring 25.

As trigger 29 is being retracted, the upper end of sear 32 contacts depending finger 34 on hammer 33 and pivots the latter to effect the required cocking action thereof. During the cocking of hammer 33, sloped surface 162 on trigger body 30 moves rearwardly beyond springbiased safety 160 to permit the withdrawal thereof out of the path of firing pin 48. Thus, as trigger 29 reaches the end of the rearward travel thereof and follower enters in dwell portion 96 of cam slot 94, sear 32 releases hammer 33 to impact against firing pin 48 and discharge the grenade cartridge 56 in the magazine firing chamber 50 then in axial alignment with barrel 20. Since the engagement between chamfer 58 in firing chamber 50 and chamfer 163 at the breech end of barrel 20 is specifically designed to mate and seal the junction therebetween against 7 the loss of firing pressure, the erratic and unpredictable variations in accuracy of fire heretofore encountered in grenade launchers with transversely fed firing chambers is completely eliminated.

As trigger 29 is released to return to the prefired position thereof under the bias of springs 108, cam plate 88 and helical cam slot 82 in yoke 80' function to advance barrel 20 in a manner reverse to that carried out during the retraction of trigger 29. Thus, once barrel 20 begins to move out of firing chamber 50, magazine 24 is free to respond to the transverse actuation of negator spring 25. However, during the initial forward movement of trigger 29, the rearward lug 112 on trigger body 30 has advanced floating cam 114 to the point of riding off lug 140 on indexing plunger 132. The timing of the functions involved and the relative bias of the springs acting on indexing plunger 132 and magazine 24 is such that the upward movement of the former is completed before the latter covers the distance between stop blocks 70. As a result, magazine 24 is halted by plunger 132 to position the next grenade cartridge 56 therein in firing alignment with barrel 20.

As trigger 29 continues to move forwardly, sloped surface 162 on trigger body 30 lifts safety 160 into blocking engagement with firing pin 48. During the remainder of the forward travel of trigger 29, sear 32 is cammed downwardly by hammer finger 34 to ride therebeneath and be thereafter biased upwardly into position to again contact the forward face of such finger 34 during the next firing retraction of trigger 29. The forward travel of trigger 29 is finally halted by contact thereof with an inclined stop surface 164 on the rear end of receiver 12.

As a result, there is here provided a unique trigger arrangement for indexing a transversely slidable magazine in a semiautomatic grenade launching firearm to successively align each firing chamber in the magazine with the barrel. The slidable actuation of the trigger is also utilized to reciprocate the barrel into and out of engagement with each firing chamber in the magazine to retain the latter against premature feeding movement upon the disengagement of the indexing plunger from the magazine. At the same time, the engagement of the breech end of the barrel in the front end of the firing chamber is utilized to seal the latter against the escape of the discharge gases generated by the firing of the grenade cartridge therein and thereby prevent the loss in projectile velocity and lack of accuracy in the flight thereof toward the target which would otherwise occur. It is also apparent that the firing and feeding functions of the firearm are both controlled by the actuation of the trigger to provide a simple and reliable mechanism particularly applicable to firearms in which the ammunition is relatively bulky and difiicult to handle.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

I claim:

1. 'In a semiautomatic firearm having a longitudinally slidable barrel, a transverse feedway rearwardly adjacent the barrel for slidably receiving a magazine containing a plurality of separate firing chambers each housing a cartridge, spring means for imparting transverse feeding movement to the magazine, and means including a trigger for firing the cartridges, the combination of:

detent means for successively indexing each cartridge into firing alignment with the barrel,

first cam means responsive to the firing movement 6f the trigger for retracting the barrel into engagement with the aligned firing chamber in the magazine, and second cam means responsive to the firing movement of the trigger for actuating said detent means to disengage from the magazine subsequent to the engagement of the barrel therewith whereby the retention of the magazine against feeding movements is continued by the barrel.

2. The combination defined in claim 1 wherein the breach end of the barrel is contoured to mate with the forward end of each firing chamber in the magazine to seal against any escape of the discharge gases generated upon the firing of each cartridge.

3. The combination defined in claim 1 including third cam means on the trigger for blocking the actuation of the firing means during the operation of said first and second cam means.

4. In a semiautomatic grenade launcher having a receiver, a barrel slidably mounted in the forward end of the receiver, a transverse feedway through the receiver rearwardly adjacent the barrel for slidably receiving a magazine containing a plurality of separate firing chambers for individually housing grenade type cartridges, spring means for imparting transverse feeding movement to the magazine, and means including a longitudinally slidable trigger for firing each cartridge in succession, improved means for indexing the magazine to feed a cartridge into firing position during each reciprocation of the trigger, comprising:

a spring-biased detent vertically disposed in the receiver for successively halting the magazine to position each firing chamber in firing alignment with the barrel,

first cam means responsive to the actuation of the trigger for reciprocating the barrel into and out of engagement with the magazine chamber in firing alignment therewith, and

second cam means responsive to the retraction of the trigger for actuating said detent to disengage from the magazine while the barrel continues to retain the magazine against feeding movement until the trigger begins to return to the prefired position thereof whereupon said detent is freed to re-engage with the magazine during the feeding movement imparted thereto by said spring means following the disengagement of the barrel from the firing chamber in alignment therewith.

5. The combination defined in claim 4 wherein the barrel is chamfered at the breech end thereof and the forward end of each firing chamber in the magazine is correspondingly chamfered to mate with the breech end of the barrel and seal the junction therebetween against the escape of the discharge gases generated by the firing of each cartridge.

6. The combination defined in claim 4 wherein said detent is a hollow plunger slidably disposed for vertical movement in the receiver and a spring is seated within said plunger for biasing the latter into the magazine feedway to engage in the underside of the magazine.

7. The combination defined in claim 4 wherein said first cam means comprises:

a cam plate secured to the forward end of the trigger,

a follower roller depending from the barrel to engage with said cam plate,

a yoke fixed to the forward end of the receiver in position to encircle the barrel, said yoke having a helical cam slot therein, and

a vertical stud extending upwardly from the barrel toengage in said helical cam slot whereby reciprocation of the trigger displaces said cam plate to rotate the barrel about the longitudinal axis thereof so that the engagement between said vertical stud thereon and said cam slot in said fixed yoke reciprocates the barrel in correspondence with the direction of trigger movement.

8. The combination defined in claim 4 wherein said second cam means comprises:

a floating cam slidably mounted in the receiver in position to actuate said detent, and

a pair of spaced lugs on the trigger straddling said floating cam for transferring the slidable movement of the trigger thereto whereby said floating cam is actuated to depress said detent out of engagement with the magazine during the retraction of the trigger and to release said detent for re-engagement with the magazine during the return of the trigger to the prefired position thereof.

9. The combination defined in claim 4 wherein the magazine feedway in the receiver includes a centrally disposed slot extending along the floor thereof and said spring means for imparting transverse feeding movement to the magazine comprises a negator spring fixedly secured at one end thereof in said centrally disposed slot in the feedway and extending therealong to terminate in a coiled portion.

10. The combination defined in claim 4 wherein said detent includes a retractor extending downwardly therefrom and through the receiver to permit manual withdrawal of the detent from engagement with the magazine.

11. In a semiautomatic grenade launcher having a receiver, a barrel slidably mounted in the forward end of the receiver, a transverse feedway through the receiver rearwardly adjacent the barrel for slidably receiving a magazine containing a plurality of laterally adjacent separate firing chambers each housing a grenade type cartridge, a negator spring for imparting transverse feeding movement to the magazine, and a firing mechanism including a longitudinally slidable trigger for firing each cartridge in turn, the combination of:

a spring biased detent plunger vertically disposed in the receiver to engage with the underside of the magazine for halting the feeding movement thereof to position the cartridge firing chamber in firing alignment with the barrel,

a forwardly elongated body on said trigger having a pair of longitudinally spaced depending lugs,

a floating cam slidably disposed in the underside of the receiver between said depending lugs on said trigger body whereby the retraction of the trigger displaces said floating cam to depress said detent plunger out of engagement with the magazine, and

cam means responsive to the initial retraction of the trigger for actuating the barrel into engagement with the firing chamber in alignment therewith to retain the magazine against feeding movement until the return of the trigger toward the prefired position thereof releases said detent plunger to re-engage with the magazine.

12. The combination defined in claim 11 wherein the receiver includes a barrel-supporting forward extension having a vertically bifurcated forward portion terminating in a yoke surrounding the barrel and provided with a laterally disposed helical cam slot therein, the receiver being also provided with a forwardly extending rectangular channel communicating with said bifurcated portion to house said elongated body of the trigger, and said cam means for actuating the barrel comprises:

a cam plate slidably seated in said bifurcated forward portion of said receiver extension in connection with the forward end of said trigger body, said plate having a laterally inclined cam slot therein,

a follower roller depending from the underside of the barrel to extend into said inclined cam slot whereby the retraction of the trigger actuates said cam plate to rotate the barrel about the longitudinal axis thereof, and

a vertical stud extending upwardly from the barrel to engage in said helical cam slot whereby the rotation imparted to the barrel by said cam plate is converted into rearward movement of the barrel into engagement with the firing chamber in firing alignment therewith.

13. The combination defined in claim 12 wherein said inclined cam slot in said cam plate includes a longitudinal dwell portion at each end thereof for permitting longitudimovement of the barrel.

14. The combination defined in claim 12 including spring means seated in said vertically bifurcated portion of said receiver extension in abutment with the rear edge of said cam plate for advancing the latter to return the trigger to the prefired position thereof and thereby reverse the camrning action on said vertical stud to withdraw the barrel out of engagement with the firing chamber and release the magazine for feeding actuation to the next position of engagement with said detent plunger.

References Cited UNITED STATES PATENTS 2,856,716 10/1958 Compton 4239.5 2,982,043 5/1961 Katz et al. 42-395 2,982,181 5/1961 Panzica 4239.5 2,982,182 5/1961 Felton et a1. 42-39.5

BENJAMIN A. BORCHELT, Primary Examiner CHARLES T. JORDAN, Assistant Examiner U .5. Cl. X.R. 421, 11 

